The present invention relates to a device and a method for the acquisition and automatic processing of data obtained from optical codes.
Hereinafter, the term xe2x80x9coptical codexe2x80x9d indicates any graphic representation which has the function of storing coded data. A specific example of an optical code comprises linear or two-dimensional codes, wherein data is coded by appropriate combinations of elements with a predetermined shape, i.e. square, rectangles or hexagons, of dark colors (normally black), separated by light elements (spaces, normally white), such as bar codes, stacked codes (including PDF417), Max codes, Datamatrix, QR codes, or colour codes etc. More generally, the term xe2x80x9coptical codexe2x80x9d further comprises other graphic forms with a data-coding function, including uncoiled printed characters (letters, numbers etc) and specific shapes (patterns) (such as stamps, logos, signatures etc).
In order to acquire optical data, optical sensors are required, converting the data coding image into electric signals, correlated to the brightness of the image dots, which can be automatically processed and decoded (through electronic processors).
At present, optical sensors are manufactured using CCD (Charge Coupled Device) technology. However, these sensors have disadvantages caused by a not always satisfactory reading performance, complexity, cost and size of the entire reading device.
Furthermore, for the manufacture of optical sensors it has already been proposed to use the CMOS technology, presently employed only in integrated electronic circuits. Hitherto, however, CCD technology has been preferred to CMOS technology, since its performance is better as to quantic efficiency, optical xe2x80x9cfill factorxe2x80x9d (i.e. the fraction of the useful area occupied by the individual detection element or pixel in order to acquire optical data), dark current leakage, reading noise and dynamics.
Recently, active pixel CMOS sensors (with an amplification section inside the pixel) have been developed, which have performance levels competitive with CCD sensors, but far greater functional capabilities. An image acquisition device can be divided into two parts, i.e. a (linear or matrix-type) optical sensor, supplying output electric signals correlated to the received light; and a unit for processing the electric signals. With the CCD technology used hitherto, whenever the processing unit has to collect data from the optical sensor; it must access all the pixels forming the optical sensor in a predetermined sequence. On the other hand, CMOS technology allows the processing unit to access any pixel directly, without having to comply with a specific order, and without the need to access all the existing pixels. In addition, CMOS sensors are fully compatible with logic circuits produced using CMOS technology itself.
The object of the invention is thus to provide a device and a method for acquiring optical data, exploiting the intrinsic advantages of CMOS technology, compared with CCD technology.
According to the present invention, a device is provided for the acquisition and automatic processing of data from optical codes, characterised, in combination, by:
a CMOS optical sensor;
an analog processing unit connected to said CMOS optical sensor;
an analog/digital conversion unit connected to said analog processing unit; and
a data-processing unit, connected to said analog/digital conversion unit.
The CMOS sensor can be of linear or matrix type; the device is also provided with a display unit and a keyboard and/or a mouse. An interface permits connection to radio, telephone; GSM or satellite systems.
The CMOS sensor and at least one of the analog and digital image processing units, are preferably integrated in a single chip; consequently the device is cheap, fast and less sensitive to noise.
The device initially advantageously acquires low-resolution images; in the low-resolution images, it looks for interest regions; then it acquires high-resolution images in the interest regions and decodes data in the high-resolution images.
According, to the invention, a method is also provided for automatically acquiring data obtained from optical codes, comprising the steps of generating an analog electric signal correlated to the brightness of an image through a CMOS optical sensor; processing said analog electric signal, in an analog manner; converting said analog electric signal into a digital signal; and processing said digital signal to extract coded optical data.
In addition, the invention relates to a device for automatic acquisition of data obtained from optical codes, characterised, in combination, by:
a CMOS optical sensor;
an analog processing unit connected to said CMOS optical sensor; and
an analog/digital conversion unit connected to said analog processing unit.